Field of the Invention
The invention applies to the manufacture of flat tension mask color cathode ray tubes. More specifically, the invention provides means for achieving registration of the aperture patterns of flat tension shadow masks and related cathodoluminescent screens.
In particular, the invention relates to a portion of the process steps employed in the manufacture of the faceplate assembly of a flat tension mask color cathode ray tube. The faceplate assembly includes a glass front panel, a support structure on the inner surface of the panel, and a tensed foil shadow mask affixed to the support structure.
In this specification, the terms "grille" and "screen" are used, and apply generally to the pattern on the inner surface of the front panel. The grille, also known as the black surround, or black matrix, is widely used to enhance contrast. It is applied to the panel first. It comprises a dark coating on the panel in which holes are formed to permit passage of light, and over which the respective colored-light-emitting phosphors are deposited to form the screen.
The holes in the grille must register with the columns of electrons passed by the holes or slots in the shadow mask. This is the primary registration requirement in a grille-equipped tube; the phosphor deposits may overlap the grille holes, hence their registration requirements are less precise.
In tubes without a grille, on the other hand, it is the phosphor deposits which must register with the columns of electrons. The word "screen", when used in the context of registration, therefore includes the grille where a grille is employed, as well as the phosphor deposits when there is no grille.
As used in this application, the terms "Q" and "Q-height" refer to the distance between the mask-receiving surface of a foil shadow mask support structure relative to the inner surface of a flat panel.